# CVE-2021-28211: Memory corruption in EDK II

> A heap overflow in EDK II allows attackers to execute arbitrary code or escalate privileges during firmware decompression.

- **Severity:** Medium 6.7 (`CVSS:3.1/AV:L/AC:L/PR:H/UI:N/S:U/C:H/I:H/A:H`)
- **Exploited in the wild:** Not known
- **Login needed:** An administrator
- **Attackable:** Local or same network only
- **Victim action needed:** Not needed
- **Fix available:** Yes
- **Published:** 11 Jun 2021
- **Updated:** 3 Aug 2024
- **Also known as:** DEBIAN-CVE-2021-28211, GHSA-9f7r-6p3j-j5wj, OESA-2021-1338, RHSA-2021:2591, RLSA-2021:2591, UBUNTU-CVE-2021-28211

## What is CVE-2021-28211?

CVE-2021-28211 is a medium-severity memory corruption vulnerability in TianoCore EDK II, published on 11 Jun 2021. It can only be exploited from the same machine or local network, with no action from the victim.

### Official description

A heap overflow in LzmaUefiDecompressGetInfo function in EDK II.

Weakness: CWE-787 (Out-of-bounds Write), CWE-122 (Heap-based Buffer Overflow)

## Which versions are affected by CVE-2021-28211?

It affects 1 product.


| Package | Ecosystem | Affected | Fixed in |
| --- | --- | --- | --- |
| `edk2` | Red Hat:enterprise_linux:8::appstream | All versions | 0:20200602gitca407c7246bf-4.el8_4.1 |
| `edk2-aarch64` | Red Hat:enterprise_linux:8::appstream | All versions | 0:20200602gitca407c7246bf-4.el8_4.1 |
| `edk2-ovmf` | Red Hat:enterprise_linux:8::appstream | All versions | 0:20200602gitca407c7246bf-4.el8_4.1 |
| `edk2` | Rocky Linux:8 | All versions | 0:20200602gitca407c7246bf-4.el8_4.1 |

Products: Tianocore Edk2.

## How do I fix CVE-2021-28211?

Apply the vendor's patch.

## Is CVE-2021-28211 being exploited?

There is no known exploitation of CVE-2021-28211 in the wild and no public exploit code.

## Other vulnerabilities in TianoCore EDK II

- [CVE-2023-45230](https://insights.sbomify.com/CVE-2023-45230/): Buffer Overflow in EDK II Network Package (high 8.3)
- [CVE-2023-45234](https://insights.sbomify.com/CVE-2023-45234/): Buffer Overflow in EDK II Network Package (high 8.3)
- [CVE-2023-45235](https://insights.sbomify.com/CVE-2023-45235/): Buffer Overflow in EDK II Network Package (high 8.3)
- [CVE-2021-28210](https://insights.sbomify.com/CVE-2021-28210/): Denial of service in EDK II (high 7.8)
- [CVE-2019-14584](https://insights.sbomify.com/CVE-2019-14584/): Null dereference in Tianocore EDK2 (high 7.8)

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2021-28211 and fix it if it is affected.

What it is: CVE-2021-28211 is a medium-severity memory corruption vulnerability in TianoCore EDK II, published on 11 Jun 2021. It can only be exploited from the same machine or local network, with no action from the victim.
Exploitation: There is no known exploitation of CVE-2021-28211 in the wild and no public exploit code.

Affected product: TianoCore EDK II. No package-level version data is available, so check the vendor advisory linked from the reference page.

Task:
1. Search the dependency manifests and lockfiles (for example package.json, package-lock.json, requirements.txt, poetry.lock, uv.lock, pom.xml, build.gradle, go.mod, Cargo.lock, Gemfile.lock) and any Dockerfiles for the affected packages, including transitive dependencies.
2. If an affected version is in use, upgrade it to the fixed version for its release line with the project's package manager, so the lockfile is regenerated. Prefer the smallest upgrade that fixes it.
3. If there is no fix, or the upgrade would break the build, do not guess: explain the risk and the safest workaround instead.
4. Run the tests and summarise what changed and why.
5. If nothing in the project is affected, say so and change nothing.

Reference: https://insights.sbomify.com/CVE-2021-28211/ (Markdown: https://insights.sbomify.com/CVE-2021-28211/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2021-28211
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2021-28211
- OSV: https://osv.dev/vulnerability/CVE-2021-28211

---
From sbomify Insights: https://insights.sbomify.com/CVE-2021-28211/
Summaries are generated and may contain mistakes; the official description above is the record.